HP 3562A Service Manual page 272

MOD E L 3562A
The co unter read/write contro l (A6 U1 07) contro l s ti m i n g for data transfer between the
U 1 09 cou nter and the local data bus. U1 07 is held in a clear state u ntil the system C P U
activates the cou nte r select s i g n a l (C O U N T E R S E LH ). Operating as a sh ift regi ster, U1 07
d rives the c h i p sel ect (CS) cou nter i n put and the NAND gates d riving the read and write
i nputs to the cou nter. After four cl ock cycles of delay, the proper configu ration s i g n a l s
cause t h e cou nte r t o write t o or read from the l ocal data bus.
System
System
Data
Data
Bus
I nterface
To CPU
I RQTSL
Trigger
To Kybd
LED
Control
Digital Source
System
System
Address
Address
Decoder
Bus
6-ASd A6
Figure
Bus
I nterrupt
Control Lines
Counter DT ACK
Block Diagram
I
To From AS
, .
Local
LO
Select, Data
Bus
Measurement
Controller
C I RC U I T D E SC R I PT I O N S
Control
Lines
Data
Point
Counter
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